Add failure analyzer for incorrect pcap file

src/main/java/ru/serega6531/packmate/exception/PcapFileNotFoundException.java

@@ -0,0 +1,15 @@
+package ru.serega6531.packmate.exception;
+
+import lombok.Data;
+import lombok.EqualsAndHashCode;
+
+import java.io.File;
+
+@EqualsAndHashCode(callSuper = true)
+@Data
+public class PcapFileNotFoundException extends RuntimeException {
+
+    private final File file;
+    private final File directory;
+
+}

src/main/java/ru/serega6531/packmate/exception/analyzer/PcapFileNotFoundFailureAnalyzer.java

@@ -0,0 +1,44 @@
+package ru.serega6531.packmate.exception.analyzer;
+
+import org.springframework.boot.diagnostics.AbstractFailureAnalyzer;
+import org.springframework.boot.diagnostics.FailureAnalysis;
+import ru.serega6531.packmate.exception.PcapFileNotFoundException;
+
+import java.io.File;
+import java.util.Arrays;
+import java.util.List;
+
+public class PcapFileNotFoundFailureAnalyzer extends AbstractFailureAnalyzer<PcapFileNotFoundException> {
+    @Override
+    protected FailureAnalysis analyze(Throwable rootFailure, PcapFileNotFoundException cause) {
+        String description = "The file " + cause.getFile().getAbsolutePath() + " was not found";
+        String existingFilesMessage;
+
+
+        File[] existingFiles = cause.getDirectory().listFiles();
+
+        if (existingFiles == null) {
+            return new FailureAnalysis(
+                    description,
+                    "Make sure you've put the pcap file to the ./pcaps directory, not the root directory. " +
+                            "The directory currently does not exist",
+                    cause
+            );
+        }
+
+
+        if (existingFiles.length == 0) {
+            existingFilesMessage = "The pcaps directory is currently empty";
+        } else {
+            List<String> existingFilesNames = Arrays.stream(existingFiles).map(File::getName).toList();
+            existingFilesMessage = "The files present in " + cause.getDirectory().getAbsolutePath() + " are: " + existingFilesNames;
+        }
+
+        return new FailureAnalysis(
+                description,
+                "Please verify the file name. Make sure you've put the pcap file to the ./pcaps directory, not the root directory.\n" +
+                        existingFilesMessage,
+                cause
+        );
+    }
+}

src/main/java/ru/serega6531/packmate/pcap/FilePcapWorker.java

@@ -6,6 +6,7 @@ import org.apache.tomcat.util.threads.InlineExecutorService;
 import org.pcap4j.core.PcapNativeException;
 import org.pcap4j.core.Pcaps;
 import org.pcap4j.packet.Packet;
+import ru.serega6531.packmate.exception.PcapFileNotFoundException;
 import ru.serega6531.packmate.model.enums.Protocol;
 import ru.serega6531.packmate.model.enums.SubscriptionMessageType;
 import ru.serega6531.packmate.model.pojo.SubscriptionMessage;
@@ -16,7 +17,6 @@ import ru.serega6531.packmate.service.SubscriptionService;
 import java.io.EOFException;
 import java.io.File;
 import java.net.UnknownHostException;
-import java.util.Arrays;
 
 @Slf4j
 public class FilePcapWorker extends AbstractPcapWorker {
@@ -32,10 +32,10 @@ public class FilePcapWorker extends AbstractPcapWorker {
         super(servicesService, streamService, localIpString);
         this.subscriptionService = subscriptionService;
 
-        file = new File("pcaps", filename);
+        File directory = new File("pcaps");
+        file = new File(directory, filename);
         if (!file.exists()) {
-            log.info("Existing files: " + Arrays.toString(new File("pcaps").listFiles()));
-            throw new IllegalArgumentException("File " + file.getAbsolutePath() + " does not exist");
+            throw new PcapFileNotFoundException(file, directory);
         }
 
         processorExecutorService = new InlineExecutorService();

src/main/resources/META-INF/spring.factories

@@ -0,0 +1,2 @@
+org.springframework.boot.diagnostics.FailureAnalyzer=\
+  ru.serega6531.packmate.exception.analyzer.PcapFileNotFoundFailureAnalyzer